Numerous support systems are already known for steerable wheels. The present invention relates more particularly to a steerable wheel support system enabling the ground clearance of the vehicle on which it is mounted to be varied. At present two types of wheel support system are known which are capable of varying a vehicle's ground clearance. In a first wheel support system, the wheel is mounted on an oscillating arm having one end fitted with means for mounting the oscillating arm to pivot relative to a vehicle body in a direction substantially parallel to a longitudinal axis of the vehicle. In known systems of this type for supporting a steerable wheel, a swivel axis is provided forming a constant angle with the oscillating arm such that the inclination of the swivel axis relative to the ground varies as the orientation of the oscillating arm is varied in order to modify ground clearance. This variation in the inclination of the swivel axis gives rise to variation in the inclination of the wheel when it is swivelled about the swivel axis in order to steer the vehicle. When the inclination of the wheel becomes excessive, the resultant force of the vehicle weight is no longer centered on the wheel tread, and this gives rise to considerable disturbance, in particular in the tire. That is why this firt type of wheel support system is generally not used for steerable wheels.
In a second type of wheel support system, the wheel is carried by an oscillating arm mounted to pivot in a direction which is substantially perpendicular to a longitudinal axis of the vehicle. In this case, a large change in vehicle ground clearance gives rise to a change in the vehicle wheel gauge, and here again, ground clearance cannot be changed to any large extent without giving rise to considerable disturbance in the tires.
An aim of the present invention is to provide a support system for a steerable vehicle wheel which enables the inclination of the wheel to be maintained substantially constant regardless of ground clearance and regardless of the steering that may be applied to the wheels.